Modern vehicles typically have one or more diagnostic systems, generally having separate computer control modules to control various functions of the vehicle. Some examples include powertrain control module (PCM), engine control module (ECM), a transmission control module (TCM), anti-locking brake system (ABS), and an air bag control module. The vehicle diagnostic systems often have self-diagnostic capability to detect and alert the driver of problems the vehicle may be encountering. When a problem is found, a diagnostic trouble code or DTC, is set within the computer's memory. DTCs are as general or as specific as the manufacturer desires.
To retrieve and decipher DTCs, an auto repair technician needs a diagnostic tool, such as a scan tool. The scan tool must, therefore, be connected to the vehicle's computer bus system to access and retrieve the DTCs. Scan tools are testing devices that interface with vehicle diagnostic systems to retrieve information from the various control modules. The scan tools are equipped to communicate in various communication protocols such as Controller Area Network (CAN), J1850 VPM and PWM, ISO 9141, Keyword 2000 and others. These communications protocols may be specific to the various automobile manufacturers. The scan tool will help the technician to diagnose and repair the vehicle based on the information the tool retrieves from it.
Another type of diagnostic system is On-Board Diagnostic II (OBD II). OBD II monitors all engine and drive train sensors and actuators for shorts, open circuits, lazy sensors and out-of-range values as well as values that do not logically fit with other powertrain data. Thus, OBD II keeps track of all of the components responsible for emissions and when one of them malfunctions, it signals the vehicle owner by illuminating a Maintenance Indicator Lamp (MIL), such as a check engine indicator. It also stores DTCs designed to help a technician find and repair the emission related problems.
The Clean Air Act of 1990 requires inspection and maintenance (I/M) programs to incorporate OBD II testing as part of a vehicle's emissions inspection program. When fully implemented, 1996 and newer model year vehicles registered in a required emission test area must be tested annually. If DTCs are present, or the diagnostic monitor software has not adequately tested the vehicle's emission control systems, the vehicle fails the emissions test. Otherwise, the vehicle passes the emissions test.
In some states, a garage can perform I/M testing along with vehicle repairs. However, the technician will use one tool for diagnostic and repair issues and another tool to perform I/M testing. The cost of purchasing both tools can be expensive for a garage, particular if it is a small independent garage.
Accordingly, it is desirable to provide a method and apparatus that allow a diagnostic tool to perform both diagnostic and I/M inspection testing.